Looking for Suggestions on my Werewolf story.

I don't have everything planned in my werewolf story yet, I'm working out all the details now. There is something I need a little help on, and I would appreciate ANY ideas! :) Here's the question...
Why would werewolves need a specific person killed? What kind of threat could a person have that would make the werewolves desperate to kill them? (or change them)
Thanks! :)

One possibility: the werewolves don't want to spread their genes, they don't want to make other werewolves because they know it's like a curse and they suffer too much. but some people want their power, their strength and their abilities so they chase the werewolves to get their genes and blood and use it to develop a werewolf army that they could use to conquer the world. and the werewolves don't want that so they will fight these people.
another possibility: the other way around. the werewolves want to conquer humans and they would do it by infecting other people turning them to werewolves. but there's a group of people that would want to stop them from doing that. and they have developed a weapon, a specific weapon derived from an ancient creature that can destroy a werewolf in just a scratch. so they would want to kill each other.
^__^

The first idea is REALLY interesting, but that would just change the ENTIRE meaning of the story I have going now :)
The second idea is good too, but I'm not sure that would work. Because, if I can, I don't want the person they are hunting to know about them. And I do already have werewolf hunters in my story, they are protecting the person being hunted.
Thank you! :)

Maybe the person the guys are protecting is going to grow up to develop something that will make the werewolves extinct in the future.
Or the person could need to be killed because they are going to be the father or mother of a future werewolf killer.